There are a total of 53 system calls (aside from ioctl) that pass a time_tor derived data structure as an argument, and in order to extend time_tto 64-bit, we have to replace them with new system calls and keep providingbackwards compatibility.

To avoid adding completely new and untested code for this purpose, weintroduce a new CONFIG_64BIT_TIME symbol. Every architecture that supportsnew 64 bit time_t syscalls enables this config via ARCH_HAS_64BIT_TIME.

After this is done for all architectures, the CONFIG_64BIT_TIME symbolcan be made a user-selected option, to enable users to build a kernelthat only provides y2038-safe system calls by making 32 time_t syscallsconditionally included based on the above config.

+config ARCH_HAS_64BIT_TIME+ def_bool n++config CONFIG_64BIT_TIME+ def_bool ARCH_HAS_64BIT_TIME+ help+ This should be selected by all architectures that need to support+ new system calls with a 64-bit time_t. This is relevant on all 32-bit+ architectures, and 64-bit architectures as part of compat syscall+ handling.+ config ARCH_NO_COHERENT_DMA_MMAP bool